Direct sulfur recovery system

Abstract

The present invention provides a method for removing sulfur species from a gas stream without the use of a sulfur species removal process, such as an amine scrub. The sulfur species are removed by directly subjecting the gas stream to a sulfur recovery process, such as a Claus or sub-dewpoint Claus process at high pressure and moderate temperatures, wherein the sulfur recovery process comprises a catalyst which does not comprise activated carbon.

1. A method for producing a sweet gas stream from a sour gas stream, wherein the sweet gas stream comprises a decreased mole fraction of a sulfur species and an increased mole fraction of a fuel species in relation to the sour gas stream, said method comprising:
 (a) subjecting the sour gas stream to a sulfur recovery process, thus producing a sweet gas stream, without first subjecting the sour gas stream to a sulfur species removal process, said sulfur recovery process comprising a catalyst which does not comprise activated carbon, wherein said sulfur recovery process is a sub-dewpoint Claus process conducted at a pressure of between 10 atm and 110 atm and at a temperature of between about 300° F. and about 500° F., wherein the sulfur recovery process converts H 2 S to elemental sulfur. 
 
     
     
       2. The method according to  claim 1 , wherein said sour gas stream is not subjected to a change in pressure prior to step (a). 
     
     
       3. The method according to  claim 1 , wherein said sour gas stream is not subjected to a change in temperature prior to step (a). 
     
     
       4. The method according to  claim 1 , wherein said sulfur recovery process is conducted at a pressure of between about 20 atm and 50 atm. 
     
     
       5. The method according to  claim 1 , wherein said sulfur recovery process is conducted at a temperature of between about 300° F. and about 400° F. 
     
     
       6. The method according to  claim 1 , wherein the sour gas stream comprises natural gas. 
     
     
       7. The method according to  claim 1 , wherein the sour gas stream comprises synthesis gas. 
     
     
       8. The method according to  claim 1 , wherein the sour gas stream comprises refinery fuel gas. 
     
     
       9. The method according to  claim 1 , wherein the sulfur species mole fraction in said sour gas stream is 10% or less. 
     
     
       10. The method according to  claim 1 , wherein said sulfur species removal process is selected from amine scrubbing, solvent absorption, adsorption, electrochemical oxidation, and membrane treatment. 
     
     
       11. The method according to  claim 1 , wherein, in addition to the sour gas stream, a gas selected from air, O 2 , SO 2  and combinations thereof, is introduced into said sulfur recovery process. 
     
     
       12. The method according to  claim 1 , wherein said elemental sulfur is a liquid. 
     
     
       13. The method according to  claim 12 , wherein said elemental sulfur collects on said catalyst, and said method further comprises regenerating said catalyst. 
     
     
       14. The method according to  claim 13 , wherein said regenerating comprises:
 a) depressurizing said sulfur recovery process; 
 b) heating said catalyst; 
 c) converting said solid sulfur and said liquid sulfur into sulfur vapor; 
 d) removing said sulfur vapor from said sulfur recovery system; and 
 e) cooling said catalyst. 
 
     
     
       15. The method according to  claim 1 , wherein said sulfur recovery process decreases the mole fraction of sulfur species in the sour gas stream by at least about 70%. 
     
     
       16. The method according to  claim 1 , wherein said sulfur recovery process decreases the mole fraction of sulfur species in the sour gas stream by at least about 98%. 
     
     
       17. The method according to  claim 1 , wherein said sulfur recovery process increases the CO 2  mole fraction in said sour gas stream. 
     
     
       18. The method according to  claim 1 , wherein a property of said sour gas stream is altered, said property selected from humidity, temperature, pressure, and combinations thereof. 
     
     
       19. The method according to  claim 1 , further comprising subjecting said sour gas stream to a steam generation process. 
     
     
       20. The method according to  claim 1 , further comprising subjecting said sweet gas stream to a steam generation process. 
     
     
       21. The method according to  claim 1 , further comprising removing particulate material from said sour gas stream. 
     
     
       22. The method according to  claim 1 , further comprising removing particulate material from said sweet gas stream. 
     
     
       23. The method according to  claim 1 , further comprising contacting said sweet gas stream with an adsorbent filter to capture residual particles. 
     
     
       24. The method according to  claim 23 , wherein said adsorbent filter is selected from activated carbon, coal, and coke. 
     
     
       25. The method according to  claim 23 , further comprising regenerating said adsorbent filter. 
     
     
       26. The method according to  claim 25 , wherein said regenerating comprises:
 a) using steam or clean gas stream to absorb said residual particles; and 
 b) subjecting the product of step (a) to said sulfur recovery process. 
 
     
     
       27. The method according to  claim 1 , further comprising subjecting said sweet gas stream to a CO 2  recovery process, thus producing a low CO 2  sweet gas stream. 
     
     
       28. The method according to  claim 1 , further comprising washing said sweet gas stream with water. 
     
     
       29. The method according to  claim 1 , further comprising separating said elemental sulfur by using an apparatus selected from a knock-out drum, coalescer, and filter.